target.c

MC68HC908EY16 LIN-BUS源码（编译环境：CodeWarriorV3.1）

/* ************************************************************************ */
/*                                                                          */
/*                  Volcano Communications technologies AB                  */
/*                            All rights reserved                           */
/*                                                                          */
/* ************************************************************************ */

/*         File: target.c                                                   */
/*  Description: Target specific functions for COS08SCI LTP example appli-  */
/*               cation                                                     */
/*                                                                          */

#include "target.h"

/* ************************************************************************ */
/* Perform initialisation of development system (if any)                    */
void init_environment(void)
{
} /* init_environment */

/* ************************************************************************ */
/* Perform initialisation of target. Initialise a free running counter at   */
/* 1MHz.                                                                    */
void init_target(void)
{
	/* Initialise debug PIN */
	INIT_SYNC_PIN();

	/* TURN on internal clock generator, and set its frq to ~16 MHz*/
	ICGMR = 53;	/* CGMXCLK ~ 16,282 MHz */
	ICGCR |= ICGCR_ICGON;
	
	/* Wait till ICG becomes stable. */
	while(!ICGCR_ICGS)
	{
		PET_WATCHDOG();
	}
	
	/* Initialise TIMA as free-run ctr.*/
   TASC_TSTOP = TASC_TRST = 1; 		/* Stop and reset counter. */

	 TASC |= TASC_PS_VALUE;      		/* Set prescaler */

   TASC_TSTOP = 0;             		/* Start timer */
   
/* If the line below is uncommented, ESCI runs from BUSCLOCK instead of CGMXCLK */
/*   CONFIG2 = ESCIBD_SRC */
} /* init_target*/

/* ************************************************************************ */
/* Read timer channel A (free running counter at 1MHz) and return current   */
/* value.                                                                   */
l_u16 l_get_us_counter (void)
{
  return(TACNTW);
} /* l_get_us_counter */

/* ************************************************************************ */
/* Restores interrupt level to the previous level, as indicated by the in-  */
/* put previous. On the hc08 family the interrupt level can only be either */
/* "interrupts enabled" or "interrupts disabled".                           */
void l_sys_irq_restore(l_irqmask previous)
{
  if (previous)
  {
    asm sei;  /* disable_interrupt */
  }
  else
  {
    asm cli;  /* enable_interrupt */
  }
} /* v_ctl_ints_restore */



/* ************************************************************************ */
/* Disable interrupts, and return the previous value of the interrupt le-   */
/* vel.                                                                     */
l_irqmask l_sys_irq_disable(void)
{
    l_irqmask x;
    
    /* Hiware specific intrinsic function that returns the interrupt flag */
    x = (l_irqmask) __isflag_int_enabled();

    /* disable_interrupt */
    asm("sei");
                                    
    /* return previous interrupt flag (disabled = 0, enabled = 1) */
    return(x);
} /* v_ctl_ints_disable */

/* ************************************************************************ */
/* Adjusts CPU internal clock generator based on bit-time measurements done */
/* by the LTP.																*/

/* Return value of L_IOCTL_RD_BIT_TIME if the CPU-clock is the nominal value */
#define L_NOMINAL_VALUE		(BUS_CLOCK*1000)/(2UL*L_BPS_i1)
#define L_MAXIMUM_VALUE		(L_NOMINAL_VALUE*23)/20
#define L_MINIMUM_VALUE		(L_NOMINAL_VALUE*3)/20
void adjust_clock(void)
{
	l_u16 bt, nm;
	nm=L_NOMINAL_VALUE;
	/* Set new clock */
	bt=l_ifc_ioctl_i1(L_IOCTL_RD_BIT_TIME,L_NULL);
	if (bt < L_MAXIMUM_VALUE
		&& bt > L_MINIMUM_VALUE
		&& bt != L_NOMINAL_VALUE)
	{
		if(bt < L_NOMINAL_VALUE)
		{
			ICGMR = ICGMR+1;
		}
		else
		{
			ICGMR = ICGMR-1;
		}
	}
	/* Start internal clock generator */
	ICGCR |= ICGCR_ICGON;
	/* Wait till clock becomes stable */
	while(!ICGCR_ICGS)
	{;}
}